I picked this action up in a local shop a few years ago.  I was told that it was an EDM Warlock but the only mark on it is an extremely low serial #.  It appears to be sized for 20mm Vulcan but has a bolt head sized for .50 BMG (The guy that ran the gun shop also said this.).  The action appears to be a giant version of a Savage.  Does anyone know of a source of different bolt heads for other case heads such as 20mm?  He said that most of these were in a necked down 20mm cartridge similar the .50 Fat Mac.  I emailed EDM arms shortly after I got it but they seemed uninterested in making parts or offering any other info.  
Anyone else have any other info or seen one?  I started milling out an aluminum chassis for it but I have lots of projects and haven't messed with it in a while.

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EDM Arms basically went out of business when Bill passed away.

His son runs his own shop in AZ, still makes guns. Look up Vigilance Rifles, maybe they can help you out?

I heard he made some 20’s but never saw one. He liked the switch caliber concept. Hope you get it built out.

Thanks! I've got a .50 barrel on it right now.  I made my own version of the Savage style barrel nut so all I need is a big spanner wrench to swap barrels.  If I could find or make a bolt head, I'd like to DD it as a 20 someday.

Honestly, doesn't look big enough for a 20.  An Anzio bolt body is 2.5" in diameter.  There are four 1.9" diameter lugs.  A 50 case swims in the bolt head.  I took a pic.  The 50 case isn't even against the side - the extractor pushes it over a little.  The bolt thrust for a 20mm is a little over 2x the 50 case based on bolt area alone.  The next problem is weight.  For anything that weighs less than 100#, even with a super efficient brake, the free recoil energy is going to SUCK.  Be VERY careful if you scale that bolt head up to a 20.  Do lots of math on the strength of the lugs on both the bolt and receiver.

What the free space with the bolt rearward?  (How long a round can it feed.)

(Crud, can't insert an image directly.  Only from a URL here.  Sorry.)

I'm aware of the high breach thrust and horrendous recoil.  I'd do lots of homework before playing around with anything bigger than .50  I took a picture of a dummy 20mm setting in the action.  If the bolt head was cut for the bigger diameter, I think it would just barely eject a loaded round.  The rifle is currently about 70 pounds.

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